The event is one in which a microscopic-blackhole was produced and decayed immediately.

The black area in the center with many particle tracks represents the inner detector (pixel detector, semiconductor tracker, and transition radiation tracker), which has been enormously magnified relative to the rest of the detector (in this view) .

The colors of the thin tracks have no significance. The thick yellow lines are the two electrons in this event. The green area is the electromagnetic calorimeter, while the red area is the hadronic calorimeter. The green and red histograms show the energy deposits by particles in the electromagnetic and hadronic calorimeters. A muon was added by hand to the event to show how it would look in the detector; it is a thick blue line in the inner detector and orange in the (blue) muon chambers.